Storage system and information management method

ABSTRACT

According to one embodiment, a storage system includes a representative node and a plurality of general nodes including a plurality of resources. Each of the general nodes stores resource status information indicating respective statuses of the plurality of resources in a first storage unit thereof. The representative node stores resource status information collected from the plurality of general nodes in a second storage unit thereof, decides whether to acquire the resource status information from the first storage unit of the general node or to acquire the resource status information from the second storage unit based on a received request, and transmits the resource status information acquired from a decided acquisition destination to an issuing source of the request.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese application JP2018-133729, filed on Jul. 13, 2018, the contents of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a storage system and an informationmanagement method, and for example, is suitable for a storage system andan information management method that manage resource status informationof resources.

2. Description of Related Art

In the related art, in a storage system configured to handle a pluralityof storage devices (hereinafter, appropriately referred to storagenodes) as one cluster by a combination thereof, a collection method or adistributed storage method is used as a method for managing operationalinformation of resources in each storage node.

The collection method is a method in which operational information ofall storage nodes is managed by a specific storage node (hereinafter,appropriately referred to a representative node) and operationalinformation of a requested object is returned in accordance with arequest from storage management software and the like (see US2011/0153603). The distributed storage method is a method in which eachstorage node retains operational information and a representative nodeinquires of each storage node about whether each storage node retainsoperational information of a requested object at a request from storagemanagement software and the like, acquires the operational informationof the requested object from an inquiry result from each storage node,and returns the acquired operational information.

In the storage system, considering that a storage node, which is not arepresentative node, is promoted to the representative node when afailure occurs, the storage node allowed to be promoted should have adisk capacity required for the representative node. Thus, it isnecessary to reduce the disk capacity required for the representativenode. In this regard, in the collection method, since operationalinformation of all storage nodes is retained in the representative node,there is a problem that the disk capacity required for therepresentative node becomes large.

On the other hand, in the distributed storage method, since theoperational information is retained in each storage node, it is possibleto reduce the disk capacity required for the representative node.However, in the distributed storage method, whenever there is a requestfrom the storage management software and the like, since each storagenode is inquired about whether the operational information of therequested object is retained, there is a problem that the load of a CPUof the entire system increases.

SUMMARY OF THE INVENTION

The invention is devised in view of the foregoing circumstances andproposes a storage system capable of appropriately managing resourcestatus information (for example, operational information) of resourcesof each storage node.

In order to solve the foregoing problems, according to the invention,there is provided a storage system including a representative node and aplurality of general nodes including a plurality of resources, whereineach of the general nodes stores resource status information indicatingrespective statuses of the plurality of resources in a first storageunit thereof, and the representative node stores resource statusinformation collected from the plurality of general nodes in a secondstorage unit thereof, decides whether to acquire the resource statusinformation from the first storage unit of the general node or toacquire the resource status information from the second storage unitbased on a received request, and transmits the resource statusinformation acquired from a decided acquisition destination to anissuing source of the request.

In the invention, an information management method in a storage systemincluding a representative node and a plurality of general nodesincluding a plurality of resources, includes a first step in which eachof the general nodes stores resource status information indicatingrespective statuses of the plurality of resources in a first storageunit thereof, a second step in which the representative node storesresource status information collected from the plurality of generalnodes in a second storage unit thereof, and a third step in which therepresentative node decides whether to acquire the resource statusinformation from the first storage unit of the general node or toacquire the resource status information from the second storage unitbased on a received request, and transmits the resource statusinformation acquired from a decided acquisition destination to anissuing source of the request.

In the above-described configuration, the resource status information isstored in the general nodes, the resource status information collectedfrom the general nodes is stored in the representative node, and theacquisition destination is changed in accordance with the receivedrequest, so that for example, it is possible to reduce a disk capacityrequired for the representative node and to reduce the number of queriesto the general nodes. As described above, the resource statusinformation is appropriately managed, so that for example, the storagesystem can be quickly and easily maintained in a normal state.

According to the invention, it is possible to realize a storage systemwith high maintainability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a configuration relatedto a storage system according to a first embodiment;

FIG. 2 is a diagram illustrating an example of a configuration relatedto an operational information collection process according to the firstembodiment;

FIG. 3 is a diagram illustrating an example of a configuration relatedto an operational information reference process according to the firstembodiment;

FIG. 4 is a diagram illustrating an example of a configuration relatedto hardware resources of a storage node according to the firstembodiment;

FIG. 5 is a diagram illustrating an example of a logical configurationrelated to a storage cluster according to the first embodiment;

FIG. 6 is a diagram illustrating an example of data stored in a memoryaccording to the first embodiment;

FIG. 7 is a diagram illustrating an example of configuration informationaccording to the first embodiment;

FIG. 8 is a diagram illustrating an example of storage node managementinformation according to the first embodiment;

FIG. 9 is a diagram illustrating an example of monitor managementinformation according to the first embodiment;

FIG. 10 is a diagram illustrating an example of monitor informationaccording to the first embodiment;

FIG. 11 is a diagram illustrating an example of summary monitorinformation according to the first embodiment;

FIG. 12 is a diagram illustrating an example of a procedure related to amonitor information collection process according to the firstembodiment;

FIG. 13 is a diagram illustrating an example of a procedure related to afirst summary monitor information collection process according to thefirst embodiment;

FIG. 14 is a diagram illustrating an example of a procedure related to asecond summary monitor information collection process according to thefirst embodiment;

FIG. 15 is a diagram illustrating an example of a procedure related to arequest response process according to the first embodiment;

FIG. 16 is a diagram illustrating an example of a procedure related toan acquisition destination detail decision process according to thefirst embodiment;

FIG. 17 is a diagram illustrating an example of a configuration relatedto a storage system according to a second embodiment;

FIG. 18 is a diagram illustrating an example of storage node managementinformation according to the second embodiment;

FIG. 19 is a diagram illustrating an example of a procedure related toprocessing at the time of reception of a request according to the secondembodiment;

FIG. 20 is a diagram illustrating an example of a configuration relatedto a storage system according to a third embodiment;

FIG. 21 is a diagram illustrating an example of storage node managementinformation according to the third embodiment;

FIG. 22 is a diagram illustrating an example of a procedure related toprocessing at the time of reception of a request according to the thirdembodiment;

FIG. 23 is a diagram illustrating an example of monitor managementinformation according to a fourth embodiment; and

FIG. 24 is a diagram illustrating an example of a procedure related to amonitor information collection process according to the fourthembodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of the invention will be described in detailwith reference to the drawings.

(1) First Embodiment

In FIG. 1, reference numeral 1 overall denotes a storage systemaccording to a first embodiment.

The storage system 1 includes storage nodes 100, a controller node 110,and compute nodes 120.

The storage nodes 100, the controller node 110, and the compute nodes120 are communicably connected to one another via a frontend network 130(a storage service network). Furthermore, the storage nodes 100 arecommunicably connected to one another via a backend network 140.

The frontend network 130 and the backend network 140 may be identical toeach other. Furthermore, in addition to the frontend network 130 and thebackend network 140, a management network may also be provided. Forexample, the storage nodes 100 and the controller node 110 may also becommunicably connected to each other via the management network.

The network (at least one of the frontend network 130, the backendnetwork 140, and the management network) may be redundant. The networkmay be a wired network or a wireless network. Furthermore, the networkmay be a different kind of network.

In the storage system 1, a storage cluster 150 includes one or morestorage nodes 100. In the storage cluster 150, a protection domain 160is defined to indicate a data distribution range in the storage cluster150. The protection domain 160 includes one or a plurality of storagenodes 100. In addition, the protection domain 160 may not be defined (itcan also be said that this is equivalent to the fact that one protectiondomain 160 is defined in the storage cluster 150).

In such a storage system 1, operational information of resources relatedto each storage node 100 is managed, which will be described in detailbelow.

FIG. 2 is a diagram illustrating an example of a configuration relatedto an operational information collection process in the storage system1. FIG. 2 illustrates storage nodes 210 and 220 as the storage nodes100.

The storage nodes 210 and 220 respectively include request control units211 and 221, storage control software 212 and 222, OS-bundled monitorprograms 213 and 223, and monitor information collection units 214 and224. The storage nodes 210 and 220 respectively include local timeseries DB 216 and 226 that store monitor information 215 and 225collected by the monitor information collection units 214 and 224.

In addition, when not distinguished from each other, the storage nodes210 and 220 may be referred to as “storage node 100”. When notdistinguished from each other, the request control units 211 and 221 maybe referred to as “request control unit 201”. When not distinguishedfrom each other, the storage control software 212 and the storagecontrol software 222 may be referred to as “storage control software202”. When not distinguished from each other, the OS-bundled monitorprograms 213 and 223 may be referred to as “OS-bundled monitor program203”. When not distinguished from each other, the monitor informationcollection units 214 and 224 may be referred to as “monitor informationcollection unit 204”. When are not distinguished from each other, themonitor information 215 and 225 may be referred to as “monitorinformation 205”. When not distinguished from each other, the local timeseries DB 216 and 226 may be referred to as “local time series DB 206”.

Additionally, although an example in which one storage control software202 is provided in the storage nodes 100 will be described, there is nolimitation in the number and type of the storage control software 202 tobe provided and the storage control software 202 may be provided in aplural number or with multiple types. Although an example in which oneOS-bundled monitor program 203 is provided in the storage nodes 100 willbe described, there is no limitation in the number and type of theOS-bundled monitor programs 203 to be provided and the OS-bundledmonitor program 203 may be provided in a plural number or with multipletypes.

The request control unit 201 receives a request from the controller node110 and the like. The storage control software 202, for example, isbasic software installed at a storage controller and acquiresoperational information (for example, the monitor information 205)indicating an operational status of the storage node 100. The OS-bundledmonitor program 203, for example, is a program subordinate to anoperating system (OS) of the storage node 100 and acquires theoperational information (for example, the monitor information 205)indicating the operational status of the storage node 100. The monitorinformation collection unit 204 collects the operational information(for example, the monitor information 205) from the storage controlsoftware 202 and the OS-bundled monitor program 203.

The monitor information 205 is information indicating an operationalstatus of resources (physical resources and/or logical resources)constituting the storage node 100 such as capacity information (forexample, capacity), performance information (for example, input/outputper second (IOPS)), and failure symptom information (for example,self-monitoring analysis and reporting technology (SMART) information ofa solid state drive (SSD) life and the like. The monitor information 205may be a counter value (for example, an IO count) or an instantaneousvalue (for example, IOPS). Furthermore, when the monitor information 205is the counter value, the monitor information 205 may be converted intothe instantaneous value when it is stored in the local time series DB206.

In the embodiment, as illustrated in FIG. 2, the storage node 210 is arepresentative node that receives a request from the controller node110. The storage node 210 serving as the representative node furtherincludes a summary monitor DB 218 that stores summary monitorinformation 217, and request distribution information 219. Hereinafter,the storage node 210 is appropriately referred to as a “representativenode” and the storage node 220, which is not the representative node, isappropriately referred to as a “general node”. In addition, as acommunication network between each general node and the representativenode, any one of the frontend network 130 and the backend network 140may be used.

In addition, the representative node includes a plurality of resources,stores resource status information (for example, the monitor information205 and operational information) indicating the status of each of theplurality of resources in a first storage unit (for example, the localtime series DB 216), and stores resource status information collectedfrom the plurality of general nodes and the first storage unit of therepresentative node in a second storage unit (for example, the summarymonitor DB 218); however, the invention is not limited thereto. Forexample, the representative node may be a dedicated storage node havingthe summary monitor DB 218 and the request distribution information 219without having the local time series DB 216. Furthermore, two or morerepresentative nodes may exist. When two or more representative nodesexist, the request distribution information 219 and the summary monitorinformation 217 of the summary monitor DB 218 may be copied between therepresentative nodes to retain duplication, or may be retained in adistributed manner.

Furthermore, for the request control unit 201, the same program ordifferent programs may be used for the representative node and thegeneral node. For the monitor information collection unit 204, the sameprogram or different programs may be used for the representative nodeand the general node.

The summary monitor information 217 is aggregate information (summarizedresource status information) that is information obtained by aggregatingoperational information. For example, the summary monitor information217 is information that is relatively frequently used on a daily basis,and is information in which the monitor information 205 has beensummarized in a time direction (for example, information 60 counts persecond have been aggregated into information per minute), or informationsummarized by aggregating the monitor information 205 of a plurality ofgeneral nodes (for example, all volumes of one node has been aggregatedas one resource).

The summary monitor information 217 may be regularly transmitted fromthe general node and may be collected or may be collected by the monitorinformation collection unit 214 of the representative node by inquiringof each general node as will be described later. When the monitorinformation collection unit 214 of the representative node inquires ofeach general node, it may be passed through the request control unit 221or the monitor information collection unit 224 of each general node orit may directly inquire of the local time series DB 226.

In the embodiment, a configuration example in which the representativenode stores the summary monitor information 217 has been described;however, the invention is not limited thereto. For example, therepresentative node may be configured to store the monitor information225 (resource status information) collected from the general nodesinstead of the summary monitor information 217. In such a configuration,the frequency at which the general node acquires resource statusinformation from each resource may be higher than the frequency at whichthe representative node acquires the resource status information fromthe general node, and the capacity of the resource status informationacquired from each resource by the general node may be larger than thecapacity of the resource status information acquired from the generalnode by the representative node.

The request distribution information 219 includes current configurationinformation, history information indicating the past movement history ofresources (indicating that the resources have been provided to anygeneral node), range information indicating a range of the storage node100 in which operational information can be distributed (indicating arange of the general node in which resources can be moved), and thelike. Additionally, the history information is information indicatinghistory regarding a storage nodes 100 in which resources have existed.For example, since the history information includes time information,the history information may be information capable of identifying thetimes at which resources have existed in any storage nodes 100.

<Operational Information Collection Procedure>

With reference to FIG. 2, a main collection procedure of operationalinformation (the monitor information 205 and the summary monitorinformation 217) in the storage system 1 will be described.

(Procedure 1)

The monitor information collection unit 204 acquires the operationalinformation from a program or a process group serving as a source of themonitor information 205, and regularly (at a fine time interval inseconds and the like) stores the operational information in the localtime series DB 206 as the monitor information 205.

(Procedure 2)

The monitor information collection unit 204 aggregates the monitorinformation 205 in the time direction or aggregates the monitorinformation 205 for each resource, and regularly (at a coarse timeinterval in minutes and the like) stores the aggregated information inthe summary monitor DB 218 of the representative node as the summarymonitor information 217. The monitor information collection unit 204aggregates the monitor information 205 as any one of an average value, asum value, a minimum value, a maximum value, the latest value, and theoldest value. In addition, there is no limitation in the aggregationmethod of values. For example, as an aggregation method other than thedescribed aggregation method, a calculation and the like of a medianvalue may be employed.

(Procedure 3)

The monitor information collection unit 204 aggregates information basedon the summary monitor information 217 collected from all the storagenodes 100, and stores the aggregated information as the summary monitorinformation 217 of a larger unit (for example, for each storage cluster150).

As described above, the storage node 100 regularly stores the monitorinformation 205 (for example, about a second, resources are employed asKey information) of each resource acquired on a non-routine basis (forexample, when a problem occurs) in the local time series DB 206.

On the other hand, the storage node 210, which is the representativenode, stores the summary monitor information 217 (for example, about aminute, time is employed as Key) acquired on a daily basis (for example,regularly) in the summary monitor DB 218, in addition to the monitorinformation 205 stored in each storage node 100.

FIG. 3 is a diagram illustrating an example of a configuration relatedto a reference process of the operational information (the monitorinformation 205 and the summary monitor information 217) in the storagesystem 1.

<Operational Information Reference Process>

With reference to FIG. 3, a main reference procedure of the operationalinformation in the storage system 1 will be described.

(Procedure 1)

The request control unit 211 of the representative node receives arequest from a management client 241 of the controller node 110.

(Procedure 2)

The request control unit 211 of the representative node acquires therequest distribution information 219 required to distribute anacquisition destination of the operational information.

(Procedure 3)

Based on the content of the request and the request distributioninformation 219, the request control unit 211 of the representative nodedetermines a storage node 100 that makes an inquiry and operationalinformation to be returned. More specifically, based on the contentincluded the request (whether it is operational information of eachresource or operational information of all clusters or whether it is thelatest operational information of resources or operational informationof a predetermined period (history) from 10 o'clock to 11 o'clock, thenumber of resources required at the same time, and the like) and therequest distribution information 219, the request control unit 211determines operational information (the monitor information 205 or thesummary monitor information 217) to be returned and the storage node 100that inquires the operational information.

(Procedure 4)

The request control unit 211 of the representative node inquires of thestorage node 100, which should make an inquiry, about necessaryoperational information. In addition, the request control unit 211 maysend out a query to each storage node 100 at once or send out the queryseveral times.

(Procedure 5)

The necessary operational information is acquired from the summarymonitor DB 218 or each storage node 100.

(Procedure 6)

The request control unit 211 of the representative node receives thenecessary operational information.

In addition, for communication between the request control units 201,the frontend network 130 may be used or the backend network 140 may beused.

(Procedure 7)

The request control unit 211 of the representative node shapes thecollected operational information and returns the shaped operationalinformation to the management client 241.

In the embodiment, the representative node receives a request; however,the invention is not limited thereto and the request control unit 221 ofthe general node may receive a request and transmit the request to therepresentative node (communication processing with the controller node110 and processing related to the collection of the operationalinformation may be distributed). Furthermore, it may be possible toemploy a configuration in which a request is transmitted between aplurality of representative nodes having copied request distributioninformation 219 and summary monitor DB 218 so as to reduce a processingload.

Additionally, since the management client 241 is an example of amanagement unit that manages the status of resources of the storage node100, it may exist in the storage node 100 or may exist outside thestorage system 1. Furthermore, it may be possible to employ aconfiguration in which a request for the request control unit 201 istransmitted from an arbitrary program, a process and the like in thestorage node 100.

FIG. 4 is a diagram illustrating an example of a configuration relatedto hardware resources of the storage node 100.

The storage node 100 is a general-purpose computer (for example, aserver device). The storage node 100 includes a central processing unit(CPU) 410, a memory 420, a plurality of drives (non-volatile memoryexpress (NVMe) drives 430, a serial attached SCSI (SAS) drive 440, aserial advanced technology attachment (SATA) drive 450), a host busadapter (HBA) 460, and a network interface card (NIC) 470.

In addition, the drive may be a non-volatile memory (storage classmemory (SCM)) and the like in addition to a hard disk drive (HDD) and asolid state drive (SSD). The HBA 460, for example, is for the frontendnetwork 130 and is a fibre channel (FC), an Ethernet (registeredtrademark), an InfiniBand and the like, and is not particularly limited.The NIC 470, for example, is for the backend network 140 and is the FC,the Ethernet, the InfiniBand and the like, and is not particularlylimited.

In the storage node 100, an example in which each hardware resource isprovided one by one has been described; the number of each hardwareresource is not particularly limited and may be one or more than one.

FIG. 5 is a diagram illustrating an example of a logical configurationrelated to the storage cluster 150.

The storage cluster 150 includes one or a plurality of protectiondomains 160, and each protection domain 160 is provided therein with oneor more pools 510 (Pool). The pool 510 may be provided across thestorage node 100 or may be closed within the storage node 100.Furthermore, in order to facilitate management, the pool 510 may have ahierarchical structure. As an example of the hierarchical structure, oneor more pools 510 closed within the storage node 100 may be combinedwith each other, one or more of the pool 510 provided across the storagenode 100 and the pool 510 closed within the storage node 100 may becombined with each other, or other configurations may be employed.

A physical storage area of the pool 510 is allocated from one or moredrives 520 or one or more chunks 530 (obtained by dividing a physicalstorage area of the drive 520) in the same protection domain 160.

A volume 540 is curved from the pool 510. The volume 540 may be closedwithin the storage node 100 or may be provided across the storage node100.

In addition, one or more drives 520 or one or more chunks 530 may bedirectly allocated to the volume 540 without defining the pool 510.

A relation between a port 550 and the volume 540 may be any one ofmany-to-many, many-to-one, one-to-many, and one-to-one. Furthermore,these relations may be across the storage node 100 or may be closedwithin the storage node 100. In addition, these relations are managed bythe storage control software 202 and the configuration information.

The operational information collection process and reference process ofthe storage node 100 are not limited to the above-described storageconfiguration (not only a specific storage configuration), and can beapplied to an arbitrary storage configuration. For example, thecollection process and the reference process can be applied to aconfiguration in which no protection domain 160 is defined, and can alsobe applied to a configuration in which no pool 510 is provided.Furthermore, the collection process and the reference process can beapplied to a configuration in which a virtual group for expressingredundant arrays of inexpensive disks (RAID) level is interposed betweenthe pool 510 and the drive 520.

FIG. 6 is a diagram illustrating an example of data stored in the memory420.

The request control unit 201 receives a request from the controller node110, acquires operational information requested by the request from itsown storage node 100 or another storage node 100, and transmits theacquired operational information to the controller node 110.

The storage control software 202 is a program group that performsfunctions of setting of configuration information 601, monitoring of aresource utilization rate and the like, virtualization of a storagedevice, and the like. The storage control software 202 includes afrontend driver for providing an interface with an exterior, acontroller driver for managing I/O to a volume and the like, a backenddriver for providing an interface with a cache and a drive (a physicaldisk), and the like. More specifically, the storage control software 202monitors the pool 510, the drive 520, the volume 540, the port 550 andthe like, and manages information (IOPS, a transfer rate and the like)on which the monitor information 205 is based.

The OS-bundled monitor program 203 acquires information (a utilizationrate of the CPU 410, a utilization rate of the memory 420, and thelike), on which the monitor information 205 is based, by a top command,a sar command and the like.

One monitor information collection unit 204 may be provided, or one ormore monitor information collection units may be provided to eachprogram, each process, or each resource to be collected.

The configuration information 601 includes information to be used todistribute the acquisition destination of the operational information.The configuration information 601 will be described later using FIG. 7.Storage node management information 602 includes information to be usedto manage the storage node 100. The storage node management information602 will be described later using FIG. 8. Monitor management information603 includes information to be used to collect the operationalinformation. The monitor management information 603 will be describedlater using FIG. 9.

In addition, it may be possible to employ a configuration in which themonitor information 205, the local time series DB 206, summary monitorinformation 207, a summary monitor DB 208, the configuration information601, the storage node management information 602, and the monitormanagement information 603 are stored in the drive 520 instead of thememory 420.

In the embodiment, only the representative node has the summary monitorinformation 207 and the summary monitor DB 208. In addition, the summarymonitor information 207 may be duplicated between the representativenodes or may be retained in a distributed manner. Each storage node 100or only the representative node may have the configuration information601 and the storage node management information 602.

The functions (the request control unit 201, the storage controlsoftware 202, the OS-bundled monitor program 203, the monitorinformation collection unit 204, the local time series DB 206, thesummary monitor DB 208 and the like) of the storage node 100, forexample, may be performed when the CPU 410 reads a program to the memory420 and executes the read program (software), may be performed byhardware such as a dedicated circuit, or may be performed by acombination of the software and the hardware. Furthermore, some of thefunctions of the storage node 100 may be performed by another computercapable of communicating with the storage node 100.

With reference to FIGS. 7 to 11, various types of information (tables)used in the storage system 1 will be described. In addition, it may beconfigured to retain values in other formats, such as a descriptionformat such as Javascript (registered trademark) object notation (JSON),instead of a table format.

FIG. 7 is a diagram illustrating an example (a configuration informationtable) of the configuration information 601. The configurationinformation table is provided for each resource type. In addition, evenin the same resource type, separate tables may be used for eachdifferent resource identification (ID). Additionally, when a separatetable is used for each resource ID, the resource ID of the table is notrequired. FIG. 7 illustrates a configuration information table 701 ofthe volume 540, a configuration information table 702 of the pool 510,and a configuration information table 703 of the chunk 530 as theconfiguration information table, and does not illustrate configurationinformation tables of other resources.

The configuration information table stores information of resources forconstructing the storage node 100, related information of the resources,and history information indicating the movement history of theresources.

As the resources, there are the storage cluster 150, the pool 510, thedrive 520, the chunk 530 in the drive 520, which allocates a physicalstorage area to the pool 510 or the volume 540, the volume 540, the port550, a bus among the compute node 120 (a host), the port 550, and thevolume 540, and the like.

For example, in the configuration information table 701 of the volume540, resource information (information of a resource ID, a capacity, anda name), resource-related information (information of a protectiondomain (PD) ID, a Pool ID, and a Node ID), and history information(movement history) are stored in a correlated manner.

The resource ID indicates an identifier capable of identifying thevolume 540. Hereinafter, all identifiers may be numerals, characterstrings, or a combination of the numerals and the character strings. Thecapacity indicates a capacity allocated to the volume 540. The nameindicates a name set in the volume 540.

The PDID indicates an identifier capable of identifying the protectiondomain 160 including the volume 540. In addition, the protection domain160 is a logical partition with a plurality of storage nodes 100 andindicates a range in which data (operational information) may bedistributed. The PDID is set by a user at the time of initialenvironment construction.

The Pool ID indicates an identifier capable of identifying the pool 510from which the volume 540 has been curved. The Node ID indicates anidentifier capable of identifying the storage node 100 provided with thevolume 540.

The movement history indicates the storage node 100 provided with thevolume 540 moved in the past. In addition, the movement history may beretained as one column in the table or may be retained as a separateconfiguration information table for each time. Furthermore, the movementhistory is updated when a movement of the volume 540 in the storage node100 occurs or a movement occurs due to failover and the like.

Similar to the configuration information table 701 of the volume 540, inthe configuration information table 702 of the pool 510, for example,information such as resource information (information such as a resourceID, a capacity, and a name), resource-related information (for example,a PDID) and the like are stored in a correlated manner. Furthermore, forexample, in the configuration information table 703 of the chunk 530,information such as resource information (information such as a resourceID, a capacity and the like), resource-related information (informationsuch as a PDID and a related pool ID) and the like are stored in acorrelated manner.

FIG. 8 is a diagram illustrating an example (a storage node managementinformation table 801) of the storage node management information 602.In the storage node management information table 801, information of anode ID, an Internet protocol (IP) address, a role, and a status isstored in a correlated manner.

The node ID indicates an identifier capable of identifying the storagenode 100.

The IP address is an example of identification information allocated tothe storage node 100 used for communication. The IP address may be anInternet protocol version 4 (IPv4) or an Internet protocol version 6(IPv6). Furthermore, instead of the IP address, a world wide name (WWN)for communicating with FC may be used or identification information usedfor communication in other protocols may be used.

The role indicates the role of the storage node 100. As the role, theremay be distinction between a main representative node of representativenodes, which representatively controls a request from the managementclient 241, and a sub-representative node that is not the mainrepresentative node, or a plurality of representative nodes may have thesame role (any representative node may control a request). In addition,the role is decided at the time of initial environment construction, butmay be changed when one of sub-representative nodes is promoted to themain representative node by majority, an ID order and the like when afailure occurs in the main representative node. Additionally, when themain representative node is selected by the logic of majority, it ispreferable that the number of representative nodes is an odd number.

The status indicates a status (normal or abnormal) when the storage node100 is normally operating.

FIG. 9 is a diagram illustrating an example (a monitor managementinformation table 901) of the monitor management information 603. In themonitor management information table 901, information of a monitorinformation type, a resource type, a metric, a collection cycle, aconfiguration condition, and a retention period is stored in acorrelated manner. The monitor management information table 901 may becommonly provided to all clusters or may be provided for each storagenode 100.

The monitor information type indicates the type of operationalinformation (the monitor information 205 “details” or the summarymonitor information 207 “summary”). The resource type indicates the typeof resources. The metric indicates an indicator for evaluating thestatus of resources (for example, an operational status). One or aplurality of metrics or an arbitrary metric may be set for eachresource.

The collection cycle indicates a cycle at which data of the metric (ametric value) is collected. The collection cycle may be fixed orvariable. When the collection cycle is variable, the collection cycle isappropriately changed by a user or a program. In addition, for example,the collection cycle is made empty, so that the metric value may not becollected. Furthermore, the collection cycle may be configured to be setin units of the resource type, set in units of the metric, set for eachset obtained by a combination of a plurality of metrics, or set in unitsof the configuration condition.

The configuration condition indicates a condition provided according tothe configuration of the storage system 1. FIG. 9 illustrates an exampleof setting a configuration condition in which the number (an example ofan indicator) of volumes 540 provided in the storage system 1 is equalto or less than 100 and is equal to or more than 101.

The configuration condition may be defined with one indicator or acombination of a plurality of indicators. Furthermore, the configurationcondition may not be provided. Furthermore, the configuration conditionmay be configured to beset in units of the resource type, set in unitsof the metric, or set for each set obtained by a combination of aplurality of metrics.

The retention period indicates a period for which data of collectedmetrics is retained. For example, a storage period (a period for whichthe above-described representative node retains the history of theresource status information) of the summary monitor information 207 islonger than a storage period (a period for which the above-describedgeneral node retains the history of the resource status information) ofthe monitor information 205. The retention period may be fixed orvariable. When the retention period is variable, the retention period isappropriately changed by a user or a program. Furthermore, the retentionperiod may be configured to be set in units of the resource type, set inunits of the metric, set for each set obtained by a combination of aplurality of metrics, or set in units of the configuration condition.

When being retained for a certain period by such a retention period, themonitor information 205 is deleted by the monitor information collectionunit 204. Similarly, when being retained for a certain period, thesummary monitor information 217 is deleted by the monitor informationcollection unit 214.

A method for changing the monitor management information 603 is notparticularly limited. For example, there may be a method for updatingthe monitor management information 603 from the management client 241via the request control unit 201, a method for updating the monitormanagement information 603 by reading a setting file, or other methods.

FIG. 10 is a diagram illustrating an example (a monitor informationtable) of the monitor information 205. An example, in which the monitorinformation table is provided for each resource type, will be described;however, the invention is not limited thereto and the monitorinformation table may be provided for each resource. FIG. 10 illustratesa monitor information table 1001 of the volume 540 and a monitorinformation table 1002 of the pool 510 as the monitor information table,and does not illustrate a monitor information table of other resources.

In the monitor information table, information of a resource ID, a time,and a metric is stored in a correlated manner.

The resource ID indicates an identifier capable of identifyingresources. In the time, a value (the time of the storage node 100) isset according to the collection cycle of the monitor managementinformation 603. In the metric, a metric value set in the monitormanagement information 603 is basically set. However, the metric may beadded or deleted. When the metric is added, past information, forexample, is made empty.

For example, in the monitor information table 1001 of the volume 540,information of a resource ID, a time, and a metric (IOPS, a transferrate and the like) is stored in a correlated manner. Furthermore, in themonitor information table 1002 of the pool 510, information of aresource ID, a time, and a metric (an amount used, a compression rateand the like) is stored in a correlated manner.

FIG. 11 is a diagram illustrating an example (a summary monitorinformation table 1101) of the summary monitor information 207. FIG. 11illustrates an example in which the summary monitor information table1101 is provided for each storage node 100, but may be provided for eachcluster without being limited thereto. Furthermore, in order toefficiently use a memory use area, a separate table may be used for eachresource.

In the summary monitor information table 1101, the summary monitorinformation 207 received from the general node and entire information(information in which the summary monitor information 207 has beenaggregated for each resource type in unity of the storage node 100, thestorage cluster 150 and the like) are stored. For example, for theentire information, when there are 100 volumes 540 in one storage node100, aggregate values (a sum value, an average value, a maximum value, aminimum value, the latest value, the oldest value and the like) of 100volumes 540 may be retained as one metric.

In the embodiment, a case where the time of the representative node isset as a key in order to facilitate the acquisition of entireinformation of the identical time will be described as an example. Morespecifically, the representative node stores a time (a time stamp) at1-minute intervals, and stores the summary monitor information 207received from the general node within one minute in the summary monitorinformation 207 as the summary monitor information 207 of the identicaltime. In such a case, the summary monitor information 207 is aggregatedfor each time and is stored as entire information. In addition, theinvention is not limited to the above-described configuration, and therepresentative node may be configured to store the summary monitorinformation 207 received from the general node as is and to specify andaggregate the summary monitor information 207 of a time specified by therequest when entire information is requested by the request.

In the time, a value (the time of the representative node) is setaccording to the collection cycle of the monitor management information603. For a metric with a long collection cycle, the same value as theprevious cycle may be set.

In addition, when the resource ID is unique among different resourcetypes, the resource type may not be provided.

With reference to FIGS. 12 to 16, various processes in the storagesystem 1 will be described.

FIG. 12 is a diagram illustrating an example of a procedure related tothe monitor information collection process. Hereinafter, an example inwhich the monitor information collection process is regularly performedwill be described; however, the invention is not limited thereto and forexample, the monitor information collection process may be performed ata designated time or at other timings.

In step S1201, the monitor information collection unit 204 confirms(refers to) the monitor management information 603.

In step S1202, the monitor information collection unit 204 confirms acollection cycle satisfying the configuration condition of the monitormanagement information 603.

In step S1203, the monitor information collection unit 204 determineswhether the time of the collection cycle has passed from a previousacquisition time with respect to a metric (a specific metric) of theconfirmed collection cycle. When it is determined that the time of thecollection cycle has passed, the monitor information collection unit 204moves the procedure to step S1204. When it is determined that the timeof the collection cycle has not passed, the monitor informationcollection unit 204 performs the process of step S1203.

In step S1204, the monitor information collection unit 204 acquires data(a metric value) of the specific metric from a target program (thestorage control software 202 or the OS-bundled monitor program 203 inthe example of the embodiment). In addition, the target program retainsinformation, which is a source of each monitor information 205, duringIO execution. For example, the frontend driver retains ReadIO count andthe like.

In step S1205, the monitor information collection unit 204 stores theacquired metric value in the local time series DB 206 as the monitorinformation 205. In such a case, the monitor information collection unit204 converts a data format according to necessity. For example, themonitor information collection unit 204 may convert an accumulated value(for example, an IO count) to an instantaneous value (for example,IOPS).

In step S1206, the monitor information collection unit 204 determineswhether the collection of metric values of all metrics to be collectedhas been completed. When it is determined that the collection has beencompleted, the monitor information collection unit 204 ends the monitorinformation collection process. When it is determined that thecollection has not been completed, the monitor information collectionunit 204 moves the procedure to step S1203.

In the processes from the above-described step S1203 to step S1206, ametric value is collected for the metric of the confirmed collectioncycle. However, the invention is not limited thereto and for example,records of the monitor management information table 901 may be set to beprocessed sequentially from the first record thereof, and a metric valueof a metric satisfying the collection cycle and the configurationcondition may be collected or a metric value may be collected by otherconfigurations. Furthermore, when a regular execution interval isidentical to the collection cycle, the processes of step S1202 and stepS1203 may be omitted.

FIG. 13 is a diagram illustrating an example of a procedure related to afirst summary monitor information collection process performed by eachstorage node 100. Hereinafter, an example in which the first summarymonitor information collection process is regularly performed will bedescribed; however, the invention is not limited thereto and forexample, the first summary monitor information collection process may beperformed at a designated time or at other timings.

In step S1301, the monitor information collection unit 204 confirms atime stamp (for example, a current time of the own storage node 100)common to all resources in the storage node 100.

In step S1302, the monitor information collection unit 204 confirms(refers to) the monitor management information 603.

In step S1303, the monitor information collection unit 204 confirms acollection cycle satisfying the configuration condition of the monitormanagement information 603.

In step S1304, the monitor information collection unit 204 determineswhether the time of the collection cycle has passed from a previousacquisition time with respect to a metric (a specific metric) of theconfirmed collection cycle. When it is determined that the time of thecollection cycle has passed, the monitor information collection unit 204moves the procedure to step S1305. When it is determined that the timeof the collection cycle has not passed, the monitor informationcollection unit 204 performs the process of step S1304. In addition, thenumber of metrics to be used in aggregation differs depending on anaggregation object (an aggregation process) and is one or more than one.

In step S1305, the monitor information collection unit 204 acquires ametric value related to the specific metric from a target program or thelocal time series DB 206. In addition, the acquisition of the metricvalue is not limited to the process of step S1305, and for example, incalculation of summary data to be described later, when calculating adifference with previous calculation, the monitor information collectionunit 204, for example, may store previous data in the memory 420 and usethe stored data.

In step S1306, the monitor information collection unit 204 calculatessummary data (a sum value and the like) based on the acquired metricvalue. For example, the monitor information collection unit 204aggregates data of 60 counts per second into data per minute (anaggregation process of time unit). Furthermore, for example, the monitorinformation collection unit 204 aggregates metric values of a pluralityof resources into a metric value of one resource (an aggregation processof a resource type unit).

In step S1307, when the monitor information collection unit 204 is notprovided in the representative node, the monitor information collectionunit 204 transmits the aggregated metric value (summary data) to therepresentative node. When the monitor information collection unit 204 isprovided in the representative node, the monitor information collectionunit 204 stores the summary data in the summary monitor DB 218 as thesummary monitor information 217. Additionally, the monitor informationcollection unit 204 can recognize the representative node by referringto the storage node management information 602, and the representativenode stores the received summary data in the summary monitor DB 218 asthe summary monitor information 217.

In step S1308, the monitor information collection unit 204 determineswhether the collection of the metric values of all metrics to becollected has been completed. When it is determined that the collectionhas been completed, the monitor information collection unit 204 ends thefirst summary monitor information collection process. When it isdetermined that the collection has not been completed, the monitorinformation collection unit 204 moves the procedure to step S1304.

In addition, in the first summary monitor information collectionprocess, a case where each storage node 100 regularly transmits summarydata has been described as an example; however, the invention is notlimited thereto and for example, the general node may be configured tocalculate and transmit summary data according to an acquisition requestof the representative node. Furthermore, when a regular executioninterval is identical to the collection cycle, the processes of stepS1303 and step S1304 may be omitted.

FIG. 14 is a diagram illustrating an example of a procedure related to asecond summary monitor information collection process performed by therepresentative node (the storage node 210). Hereinafter, an example inwhich the second summary monitor information collection process isregularly performed will be described; however, the invention is notlimited thereto and for example, the second summary monitor informationcollection process may be performed at a designated time or at othertimings. Furthermore, when a regular execution interval is identical tothe collection cycle, processes of step S1403 and step S1404 may beomitted.

In step S1401, the monitor information collection unit 214 confirms atime stamp (for example, a current time of the representative node)common to all resources in the storage system 1.

In step S1402, the monitor information collection unit 214 confirms(refers to) the monitor management information 603.

In step S1403, the monitor information collection unit 214 confirms acollection cycle satisfying the configuration condition of the monitormanagement information 603.

In step S1404, the monitor information collection unit 214 determineswhether the time of the collection cycle has passed from a previousacquisition time with respect to a metric (a specific metric) of theconfirmed collection cycle. When it is determined that the time of thecollection cycle has passed, the monitor information collection unit 214moves the procedure to step S1405. When it is determined that the timeof the collection cycle has not passed, the monitor informationcollection unit 214 performs the process of step S1404. In addition, thenumber of metrics used in aggregation differs depending on anaggregation object (an aggregation process) and is one or more than one.

In step S1405, the monitor information collection unit 214 acquires thesummary monitor information 217 (a metric value) related to the specificmetric from the summary monitor DB 218. In addition, the acquisition ofthe metric value is not limited to the process of step S1405, and forexample, in calculation of summary data to be described later, whencalculating a difference with previous calculation, the monitorinformation collection unit 214, for example, may store previous data inthe memory 420 and use the stored data.

In step S1406, the monitor information collection unit 214 calculatessummary data (a sum value and the like) based on the acquired metricvalue. For example, the monitor information collection unit 214aggregates data of all the storage nodes 100 belonging to one clusterinto data of a cluster unit (an aggregation process of a resource typeunit). More specifically, the monitor information collection unit 214calculates the sum value of the used capacities of the volumes 540 inall the storage nodes 100 belonging to one cluster, or calculates thesum value of the IOPSs of the volumes 540 in all the storage nodes 100belonging to one cluster.

In step S1407, the monitor information collection unit 214 stores theaggregated metric value (summary data) in the summary monitor DB 218 asthe summary monitor information 217.

In step S1408, the monitor information collection unit 214 determineswhether the collection of metric values of all metrics to be collectedhas been completed. When it is determined that the collection has beencompleted, the monitor information collection unit 214 ends the secondsummary monitor information collection process. When it is determinedthat the collection has not been completed, the monitor informationcollection unit 214 moves the procedure to step S1404.

FIG. 15 is a diagram illustrating an example of a procedure related to arequest response process performed by the representative node (thestorage node 210). The request response process is performed based onthe fact that the request control unit 211 of the representative nodereceives a request from the controller node 110.

In step S1501, the request control unit 211 receives a request from thecontroller node 110.

In step S1502, the request control unit 211 determines whether anacquisition destination of operational information is the summarymonitor DB 218 only by the request. When it can be determined that theacquisition destination of the operational information is the summarymonitor DB 218 only by the request, the request control unit 211 movesthe procedure to step S1503. When it is not possible to determine thatthe acquisition destination of the operational information is thesummary monitor DB 218 only by the request, the request control unit 211moves the procedure to step S1504.

For example, when neither time nor resource ID has been designated inthe request, the request control unit 211 determines that the latestsummary monitor information 217 of all the current resources isrequested and determines that the acquisition destination of theoperational information is the summary monitor DB 218 only by therequest.

Furthermore, for example, when the resource ID has been designated inthe request but no time has been designated in the request and when arequest object has not been explicitly designated to be the monitorinformation 205, the request control unit 211 determines that the latestsummary monitor information 217 of the current designated resource isrequested and determines that the acquisition destination of theoperational information is the summary monitor DB 218 only by therequest.

In step S1503, the request control unit 211 inquires of the summarymonitor DB 218, acquires operational information requested by therequest, and moves the procedure to step S1509.

As described above, when it is determined that aggregate information(for example, the summary monitor information 217) stored in the secondstorage unit (for example, the summary monitor DB 218, the summarymonitor information table 1101, the memory 420, or the drive) isrequested in the request, the representative node acquires the aggregateinformation from the second storage unit and transmits the acquiredaggregate information to a management unit (for example, the controllernode 110, the management client 241, an arbitrary program in the storagenode 100, or a process).

In such a case, when the acquired aggregation is information that isrelatively high frequently requested from the management unit, it ispossible to decide the acquisition destination by analyzing the requestwithout confirming the configuration information 601 according to theabove-described configuration, so that it is possible to improveresponse performance for a request.

More broadly, the representative node determines whether it is possibleto acquire resource status information on the above-described requestfrom the above-described second storage unit, and acquires the resourcestatus information from the first storage unit of the above-describedgeneral node when it is not possible to acquire the resource statusinformation. According to such a configuration, it is possible topreferentially acquire the resource status information from the secondstorage unit, so that it is possible to improve response performance fora request.

In step S1504, the request control unit 211 refers to the requestdistribution information 219 (the configuration information 601 and thelike).

In step S1505, the request control unit 211 performs an acquisitiondestination detail decision process. The acquisition destination detaildecision process will be described later with reference to FIG. 16, butin the acquisition destination detail decision process, the storage node100 of the acquisition destination of the operational informationrequested by the request is decided.

In step S1506, the request control unit 211 determines whether theacquisition destination of the operational information is the summarymonitor DB 218. When it is determined that the acquisition destinationof the operational information is the summary monitor DB 218, therequest control unit 211 moves the procedure to step S1503. When it isdetermined that the acquisition destination of the operationalinformation is not the summary monitor DB 218, the request control unit211 moves the procedure to step S1507.

In step S1507, the request control unit 211 inquires of the requestcontrol unit 201 of one or a plurality of storage nodes 100 (decisionnodes) decided as the acquisition destination of the operationalinformation about the operational information requested by the request.Upon receipt of the query, the request control unit 201 inquires of thelocal time series DB 206 about the operational information requested bythe request, and transmits the operational information acquired from thelocal time series DB 206 to the representative node (the request controlunit 211).

In step S1508, the request control unit 211 acquires the operationalinformation requested by the request from the decision node and movesthe procedure to step S1509.

In step S1509, the request control unit 211 shapes the acquiredoperational information.

In step S1510, the request control unit 211 transmits the shapedoperational information to the controller node 110 having transmittedthe request (response return), and ends the request response process.

FIG. 16 is a diagram illustrating an example of a procedure related tothe acquisition destination detail decision process.

In step S1601, the request control unit 211 determines whether detailedinformation (the monitor information 205) is explicitly requested in arequest. When it is determined that the detailed information isexplicitly requested, the request control unit 211 moves the procedureto step S1602. When it is determined that the detailed information isnot explicitly requested, the request control unit 211 moves theprocedure to step S1606.

In step S1602, based on the configuration information 601, the requestcontrol unit 211 determines whether a value has been stored in movementhistory with respect to a designated resource (whether the movementhistory is known). When it is determined that the value has been storedin the movement history, the request control unit 211 moves theprocedure to step S1603. When it is determined that the value has notbeen stored in the movement history, the request control unit 211 movesthe procedure to step S1604.

In step S1603, based on the movement history, the request control unit211 specifies a storage node 100 (group) in which resources has existed,and moves the procedure to step S1605.

As described above, the representative node analyzes the request,determines whether predetermined resource status information (forexample, the monitor information 205) is requested from the managementunit, and specifies a general node (a general node retaining requestedresource status information) provided with a resource related to thepredetermined resource status information based on history information(for example, the movement information of the configuration information601) when it is determined that the predetermined resource statusinformation is requested. By such specifying, since it is possible toappropriately narrow down acquisition destinations of the resourcestatus information, it is possible to remove a load to the storage node100 due to an unnecessary query and improve response performance for arequest.

In step S1604, based on a relation among the protection domain 160, thechunk 530 and the like, the request control unit 211 specifies a storagenode 100 (group) in which resources may have existed, and moves theprocedure to step S1605.

As described above, the representative node analyzes the request,determines whether predetermined resource status information (forexample, the monitor information 205) is requested from the managementunit, and specifies a general node in a range, in which a resourcerelated to the predetermined resource status information can be moved,based on range information (for example, the configuration information601) when it is determined that the predetermined resource statusinformation is requested. By such specifying, since it is possible tonarrow down acquisition destinations of the resource status informationto a certain extent, it is possible to reduce a load to the storage node100 due to an unnecessary query and improve response performance for arequest, as compared with a case where the acquisition destinations arenot narrowed down.

More broadly, in the case of acquiring the resource status informationfrom the above-described general node, the representative node specifiesthe above-described general node based on history information indicatingany one of the plurality of general nodes, which is provided with aresource that is a target of the resource status information or rangeinformation indicating a range in which the above-described resource canbe moved, and acquires the resource status information.

In step S1605, the request control unit 211 decides to inquire of thespecified storage node 100 (group) and ends the acquisition destinationdetail decision process.

In step S1606, the request control unit 211 determines whether toacquire operational information from the storage node 100. When it isdetermined to acquire the operational information from the storage node100, the request control unit 211 moves the procedure to step S1602.When it is determined not to acquire the operational information fromthe storage node 100, the request control unit 211 moves the procedureto step S1607.

For example, when the number of resources designated in the request issmaller than a certain number, the request control unit 211 maydetermine to acquire the operational information from the storage node100. In such a case, the certain number may differ depending onsituations. For example, the certain number may be decided by comparingthe counted number of monitor information 205 to be counted with thenumber of storage nodes 100 that makes an inquiry in terms of a quantity(a ratio), or may be decided by measuring response performance in whichtime-keyed data is referred to for each resource and comparing thenumber of storage nodes 100 that makes an inquiry with the responseperformance.

In addition, since there is a possibility that the volume 540 has beenmoved among the storage nodes 100 in the past, there are cases where aplurality of storage nodes 100 are inquired with reference to movementinformation (see step S1603). Furthermore, when it is not possible toretain the movement information due to a memory size problem, eventhough there is no movement information, a plurality of storage nodes100 may be inquired such as all storage nodes 100 in the protectiondomain 160 with potential movement and all storage nodes 100 with arelated chunk 530 (see step S1604).

Furthermore, for example, when the number of resources designated in therequest is larger than the certain number, the request control unit 211may determine to acquire the operational information from the summarymonitor DB 218.

When the history of the operational information has been designated, itis usual to inquire of each storage node 100, but when more than acertain number of resources are simultaneously designated, referenceprocess efficiency becomes better by referring to the time-keyed summarymonitor information 217 of the summary monitor DB 218 provided in therepresentative node. For example, when a number obtained by countingtime of operational information to be acquired is more than 1,000, itmay be faster to refer back to the summary monitor information 217 ofthe summary monitor DB 218 rather than inquiring of 1,000 storage nodes100 and in such a case, the request control unit 211 determines that itis returned from the summary monitor DB 218.

As described above, based on the number of the above-described generalnodes, in which acquisition is performed, when the resource statusinformation is set to be acquired from the above-described generalnodes, the above-described representative node decides whether toacquire the resource status information from either the above-describedgeneral node or the second storage unit.

In step S1607, the request control unit 211 decides to inquire of thesummary monitor DB 218 and ends the acquisition destination detaildecision process.

As described above, the representative node analyzes the request, andwhen it is determined that designation for requesting the resourcestatus information stored in the first storage unit (for example, thelocal time series DB 206, the monitor information table, the memory 420,and the drive) does not exist in the request, the representative nodedecides whether to acquire the resource status information from thefirst storage unit or acquire the aggregate information from the secondstorage unit based on response performance of the general node. In sucha configuration, an object, in which a process required for acquisitionis fast, is decided as an acquisition destination, so that it ispossible to improve response performance for a request.

In the above-described first embodiment, for example, the storage systemis a storage system including a representative node and a plurality ofgeneral nodes including a plurality of resources, and theabove-described each general node stores resource status informationindicating respective statuses of the plurality of resources in a firststorage unit thereof and the above-described representative node storesresource status information collected from the plurality of generalnodes in a second storage unit thereof, decides whether to acquire theresource status information from the first storage unit of theabove-described general node or to acquire the resource statusinformation from the above-described second storage unit based on areceived request, and transmits the resource status information acquiredfrom the decided acquisition destination to an issuing source of theabove-described request.

In the above-described configuration, the resource status information isretained in the general node, the resource status information collectedfrom the general node is retained in the representative node, and theacquisition destination is changed based on the received request, sothat it is possible to reduce a disk capacity necessary for therepresentative node and to reduce the load of the CPU of the entirestorage system.

Furthermore, according to the above-described configuration, forexample, even when there is an increase in general nodes to be managed,it is possible to appropriately manage resource status information ofeach general node.

(2) Second Embodiment

When a storage system becomes large (when the number of storage nodes tobe managed is large), if one representative node performs processing atthe time of reception of all requests from the controller node, there isa problem that response performance is degraded. In this regard, in theembodiment, a main representative node and a sub-representative nodeshare processing at the time of reception of a request, so that responseperformance is improved.

The embodiment is mainly different from the first embodiment in that amain representative node and a sub-representative node are provided asrepresentative nodes and the range of a storage node taken charge of byeach representative node is specified.

With reference to FIGS. 17 to 19, the embodiment will be described. Thesame elements as those of the first embodiment are denoted by the samereference numerals, and a description thereof will be omitted.

FIG. 17 is a diagram illustrating an example of a configuration relatedto a storage system 2 according to the embodiment. The storage system 2includes a storage node 1710 (a main representative node), a storagenode 210 (a sub-representative node), a storage node 220 (a generalnode) and the like.

The storage node 1710 serving as the main representative node includes arequest control unit 1711 that receives a request from the controllernode 110 or transmits the request to a sub-representative node, andstorage node management information 1712 in which the storage node 220of a general node to be taken charge of has been defined. The storagenode management information 1712 will be described later using FIG. 18.Furthermore, the request control unit 1711 will be described later usingFIG. 19.

When a request is received, the main representative node, for example,transmits the request to the sub-representative node. When the requestis received, the sub-representative node performs the same process asthat of the representative node of the first embodiment within its ownresponsibility.

<Operational Information Reference Procedure>

A main reference procedure of operational information will be describedbelow.

(Procedure 1)

The request control unit 1711 of the main representative node receives arequest from the management client 241 of the controller node 110.

(Procedure 2)

The request control unit 1711 of the main representative node acquiresinformation on a representative node based on the storage nodemanagement information 1712.

(Procedure 3)

The request control unit 1711 of the main representative node transmitsthe request to the sub-representative node based on the content of therequest.

(Procedure 4)

Based on the request distribution information 219, the request controlunits 211 and 1711 of each main representative node acquire informationrequired for the distribution of an acquisition destination ofoperational information.

(Procedure 5)

Based on the content of the request and the request distributioninformation 219, the request control units 211 and 1711 of each mainrepresentative node determine the storage node 100 that makes an inquiryand operational information to be returned.

(Procedure 6)

The request control units 211 and 1711 of each main representative nodeinquire of the storage node 100, which should make an inquiry, aboutnecessary operational information. In addition, the request controlunits 211 and 1711 may send out a query to each storage node 100 at onceor send out the query several times.

(Procedure 7)

The necessary operational information is acquired from the summarymonitor DB 218 or each storage node 100.

(Procedure 8)

The request control unit 1711 of the main representative node receivesthe necessary operational information.

(Procedure 9)

The request control unit 1711 of the main representative node shapes thecollected operational information and returns the shaped operationalinformation to the management client 241.

FIG. 18 is a diagram illustrating an example (a storage node managementinformation table 1801) of the storage node management information 1712.In the storage node management information table 1801, information of afault set is stored in a correlated manner in addition to information ofthe storage node management information 602.

The fault set is identification information indicating a set of storagenodes 100 that do not stop the entire storage system 2 even thoughfailures occur at the same time. For example, the same fault set iscorrelated with a group of storage nodes 100 using the same rack, thesame power, and the same switch. A group of storage nodes 100 with thesame fault set is a range taken charge of by each representative node.In addition, the fault set, for example, is set at the time of initialenvironment construction.

In the embodiment, a representative node is set for each fault set.Among a plurality of representative nodes, one representative node isset as a main representative node and remaining representative nodes areset as sub-representative nodes.

The coverage of the representative node is not limited to the use of theabove-described fault set. For example, it is not fixed like the faultset, but the setting of the coverage may be configured to be dynamicallychanged (for example, decision of the number of representative nodes andthe number of general nodes in accordance with the number of storagenodes 100, dynamical allocation of identification information capable ofidentifying general nodes belonging to a representative node, and thelike).

FIG. 19 is a diagram illustrating an example of a procedure related toprocessing at the time of reception of a request by the request controlunit 1711. The processing at the time of reception of the request isperformed based on the fact that the request control unit 1711 of themain representative node receives a request from the controller node110.

In step S1901, the request control unit 1711 receives a request from thecontroller node 110.

In step S1902, the request control unit 1711 transmits the request tothe sub-representative node based on the content of the request and thestorage node management information 1712. For example, the requestcontrol unit 1711 analyzes the content of the request, and when it isdetermined that operational information within a designated time of aspecific volume 540 has been requested, the request control unit 1711specifies the storage node 220 provided with the specific volume 540based on the request distribution information 219, specifies asub-representative node responsible for the specified storage node 220based on the storage node management information 1712, and transmits therequest to the specified sub-representative node. In addition, since acase where the request is not transmitted to the sub-representative nodeis the same as that in the first embodiment, illustration anddescription thereof will be omitted.

In step S1903, a request response process is performed. In addition, therequest response process is basically the same as the processillustrated in FIG. 15, and a transmission source and a transmissiondestination of the request are not the controller node 110 but the mainrepresentative node.

In step S1904, the request control unit 1711 shapes operationalinformation returned from each sub-representative node.

In step S1905, the request control unit 1711 transmits the shapedoperational information to the controller node 110 and ends the requestresponse process.

According to the above-described second embodiment, for example, in thestorage system, the above-described main representative node specifies ageneral node that is a target of the above-described received request,specifies a representative node that manages the above-describedspecified general node based on management information (for example, thestorage node management information 1712) in which a management relationbetween the above-described representative node and general node hasbeen defined, and allows the above-described specified representativenode to acquire the request, and the above-described specifiedrepresentative node acquires the above-described request, decideswhether to acquire the resource status information from theabove-described general node or to acquire the resource statusinformation from the above-described second storage unit, and transmitsthe resource status information acquired from the decided acquisitiondestination to an issuing source of the above-described request.

In the above-described configuration, a plurality of representativenodes share the request response process, so that it is possible todistribute a load applied to the request response process.

Furthermore, in the above-described configuration, for example, evenwhen general nodes to be managed has increased, general nodes takencharge of by the representative node are limited, so that it is possibleto appropriately manage resource status information of each general nodewithout increasing a load of the representative node.

In the embodiment, a configuration example in which the representativenode includes common request distribution information 219 has beendescribed; however, the invention is not limited thereto. For example,each representative node may have request distribution information(configuration information) of a range to be shared. According to such aconfiguration, it is possible to reduce an amount of the distributioninformation, so that it is possible to reduce time required forspecifying (searching for) a general node that inquires operationalinformation.

(3) Third Embodiment

When a storage system becomes large (when the number of storage nodes tobe managed is large), if one representative node performs all requestresponse processes for requests from the controller node, there is aproblem that response performance is degraded. In this regard, in theembodiment, a main representative node shares the request responseprocess according to the state of a sub-representative node, so thatresponse performance is improved.

As the state of the sub-representative node, it is assumed that thereare various states such as whether the sub-representative node is in thelatest state and whether a processing load of the sub-representativenode is high. Hereinafter, a description will be provided for aconfiguration example in which a main representative node determines theversion of configuration information of a sub-representative node (is itconfiguration information at what point in time? or is it the latestconfiguration information?) and shares processing by transmitting arequest to the sub-representative node.

With reference to FIGS. 20 to 22, the embodiment will be described. Thesame elements as those of the first embodiment are denoted by the samereference numerals, and a description thereof will be omitted.

FIG. 20 is a diagram illustrating an example of a configuration relatedto a storage system 3 according to the embodiment. The storage system 3includes a storage node 2010 (a main representative node), a storagenode 2020 (a sub-representative node), and a storage node 220 (a generalnode).

The storage node 2010 serving as the main representative node includes arequest control unit 2011, a storage control software 2012, anOS-bundled monitor program 2013, a monitor information collection unit2014, monitor information 2015, a local time series DB 2016, summarymonitor information 2017, a summary monitor DB 2018, first requestdistribution information 2019A, and second request distributioninformation 2019B. Since the elements 2012 to 2018 of the mainrepresentative node are identical to the elements 212 to 218 of the mainrepresentative node of the first embodiment, a description thereof willbe omitted.

The request control unit 2011 selects a sub-representative node, whichis an acquisition destination of operational information, based on thefirst request distribution information 2019A when a request is receivedfrom the controller node 110, and transmits the request to the selectedsub-representative node. When no sub-representative node is selected asthe acquisition destination, the request control unit 2011 determinesthe storage node 100, which acquires the operational information, andoperational information to be returned based on the content of thereceived request and the second request distribution information 2019B.

The first request distribution information 2019A is an example of nodestatus information indicating the status of a representative node and isinformation used in the distribution of a request from the controllernode 110. More specifically, the first request distribution information2019A is information for determining a representative node, to which therequest is distributed, in order to distribute the load of therepresentative node. For example, the first request distributioninformation 2019A is information (for example, storage node managementinformation to be described later) including the time at which thesecond request distribution information 2019B (for example, theconfiguration information 601) has been synchronized. An example of thestorage node management information is illustrated in FIG. 21.

The second request distribution information 2019B is information used tospecify a location of operational information. For example, the secondrequest distribution information 2019B is information identical to therequest distribution information 219 and is synchronized (duplicated)between the main representative node and the sub-representative node.

The storage node 2020 serving as the sub-representative node includes arequest control unit 2021, storage control software 2022, an OS-bundledmonitor program 2023, a monitor information collection unit 2024,monitor information 2025, a local time series DB 2026, and secondrequest distribution information 2027. Since the elements 2021 to 2026of the sub-representative node are identical to the elements 211 to 216of the main representative node of the first embodiment, a descriptionthereof will be omitted.

The second request distribution information 2027 is obtained throughsynchronization (duplication) of the second request distributioninformation 2019B. Based on the content of the transmitted request andthe second request distribution information 2027, the request controlunit 2021 determines the storage node 100, which acquires theoperational information, and operational information to be returned.

In addition, the request control unit 2011 of the main representativenode, the request control unit 2021 of the sub-representative node, andthe request control unit 221 of the general node may be implemented withthe same program or different programs.

<Operational Information Reference Procedure>

A main reference procedure of operational information will be describedbelow.

(Procedure 1)

The request control unit 2011 of the main representative node receives arequest from the management client 241 of the controller node 110.

(Procedure 2)

The request control unit 2011 of the main representative node acquiresthe first request distribution information 2019A used for requestdistribution.

(Procedure 3)

The request control unit 2011 of the main representative node selects arepresentative node (own or a sub-representative node), which is adistribution destination of the request, based on the first requestdistribution information 2019A.

(Procedure 4)

When the selected representative node is a sub-representative node, therequest control unit 2011 of the main representative node transmits therequest to the sub-representative node.

(Procedure 5)

Each representative node (for example, the request control unit 2011 or2021) acquires second request distribution information (for example, thesecond request distribution information 2019B and 2027) used to acquireoperational information.

(Procedure 6)

Based on the second request distribution information (for example, thesecond request distribution information 2019B and 2027), eachrepresentative node (for example, the request control unit 2011 or 2021)acquires information necessary for distributing an acquisitiondestination of the operational information.

(Procedure 7)

Based on the content of the request and the second request distributioninformation (for example, the second request distribution information2019B and 2027), each representative node (for example, the requestcontrol unit 2011 or 2021) determines the storage node 100 that makes aninquiry and operational information to be returned.

(Procedure 8)

Each representative node (for example, the request control unit 2011 or2021) inquires of the storage node 100, which should make an inquiry,about necessary operational information. In addition, the requestcontrol units 2011 and 2021 may send out a query to each storage node100 at once or send out the query several times.

(Procedure 9)

The necessary operational information is acquired from the summarymonitor DB 218 or each storage node 100.

(Procedure 10)

The request control unit 2011 of the main representative node receivesthe necessary operational information.

(Procedure 11)

The request control unit 2011 of the main representative node shapes thecollected operational information and returns the shaped operationalinformation to the management client 241.

FIG. 21 is a diagram illustrating an example (a storage node managementinformation table 2101) of the storage node management information.

In the storage node management information table 2101, information of aconfiguration information synchronization time is stored in a correlatedmanner in addition to the storage node management information 602.

The configuration information synchronization time indicates the time atwhich the configuration information 601 (the second request distributioninformation 2019B and 2027) is synchronized between representativenodes.

When a request for acquiring the latest operational information isreceived, the synchronization time of the configuration information 601needs to be up-to-date, but when a request for acquiring the pastoperational information is received, even though the synchronizationtime of the configuration information 601 is the old time, there is noproblem if the synchronization time of the configuration information 601is newer than the past. When the configuration information 601 isup-to-date, there is no problem in any of requests. That is, based onthe synchronization time of the configuration information 601 retainedin each representative node, it is possible to perform a requestdistribution process.

Information used for the request distribution process is not limited tothe information of the configuration information synchronization time,and it may be possible to employ the usage amount and the like ofresources of the storage node 100 such as the load of the CPU 410 of thestorage node 100. In addition, the information used for the requestdistribution process may be configured to be updated when the mainrepresentative node regularly inquires of each sub-representative node,may be configured to be updated when information is transmitted fromeach sub-representative node to the main representative node, or may beconfigured to be updated via a recording medium.

FIG. 22 is a diagram illustrating an example of a procedure related toprocessing at the time of reception of a request by the request controlunit 2011. The processing at the time of reception of the request isperformed based on the fact that the request control unit 2011 of themain representative node receives a request from the controller node110.

In step S2201, the request control unit 2011 receives a request from thecontroller node 110.

In step S2202, the request control unit 2011 determines whether thereare sub-representative nodes satisfying a condition of the request. Forexample, when it is determined that the request is a request foracquiring the latest operational information, the request control unit2011 determines whether there are sub-representative nodes having thelatest configuration information 601 (configuration information 601having the same update date as that of a main representative node).Furthermore, for example, when it is determined that the request is arequest for acquiring the past operational information, the requestcontrol unit 2011 determines whether there are sub-representative nodeshaving configuration information 601 having an update date newer thanthe past.

When it is determined that there are the sub-representative nodessatisfying the condition of the request, the request control unit 2011moves the procedure to step S2203, and when it is determined that thereare no sub-representative nodes satisfying the condition of the request,the request control unit 2011 moves the procedure to step S2206.

In step S2203, the request control unit 2011 selects onesub-representative node satisfying the condition of the request andtransmits the request to the selected sub-representative node.

In step S2204, the request control unit 2011 performs a request responseprocess. In addition, the request response process is basically the sameas the process illustrated in FIG. 15, and a transmission source and atransmission destination of the request are not the controller node 110but the main representative node.

In step S2205, the request control unit 2011 shapes operationalinformation returned from each sub-representative node.

In step S2206, the request control unit 2011 performs a request responseprocess. In addition, since the request response process is basicallythe same as the process illustrated in FIG. 15, a description thereofwill be omitted.

In step S2207, the request control unit 2011 transmits the shapedoperational information to the controller node 110 and ends the requestresponse process.

In the above-described third embodiment, for example, in the storagesystem, the above-described main representative node determines whetherthe above-described request is to be processed by a sub-representativenode, which is the above-described specified representative node, basedon the node status information (for example, the information of theconfiguration information synchronization time and the usage rate of theCPU of the main representative node and the sub-representative node)indicating the status of the above-described main representative nodeand the above-described sub-representative node, and transmits theabove-described request to the above-described sub-representative nodewhen it is determined that the above-described request is to beprocessed.

According to the above-described configuration, when time is requiredfor the synchronization of configuration information (the seconddistribution information) between the main representative node and thesub-representative node, a synchronization status (a synchronizationtime) between each representative node is taken into consideration inorder to perform processing with consistency, so that it is possible todistribute the request.

Furthermore, in a case where the status of the representative node isset as the status of a resource, when there is a difference in aprocessing load between representative nodes, a load applied to theresource is taken into consideration, so that it is possible todistribute the request to a representative node with the lowest load forexample.

According to the embodiment, the request response process can beperformed in accordance with the status of the representative node, sothat it is possible to improve response performance for a request.

(4) Fourth Embodiment

In a large storage system, when operational information is always storedin time series, there is a problem that the amount of disk usage becomesenormous. In this regard, in the embodiment, in order to reduce theamount of disk usage, the operational information is not always stored,and is stored when there is a problem.

With reference to FIGS. 23 and 24, the embodiment will be described. Thesame elements as those of the first embodiment are denoted by the samereference numerals, and a description thereof will be omitted.

FIG. 23 is a diagram illustrating an example (a monitor managementinformation table 2301) of the monitor management information. In themonitor management information table 2301, information of a thresholdupper limit and a threshold lower limit are stored in a correlatedmanner in addition to the monitor management information 603.

When a metric value of a resource exceeds a threshold value (when themetric value of the resource exceeds the threshold upper limit or whenthe metric value of the resource becomes less than the threshold lowerlimit), a process is performed to store the metric value in the localtime series DB 206 as the monitor information 205.

The threshold upper limit and/or the threshold lower limit may be fixedor variable, may be set by a user, or may be automatically changed by aprogram. For example, as an example of the automatic change, there is amethod in which a trend is acquired for a certain period of time, suchas baseline monitoring, to allow the program to learn a normal state anda range of the normal state is set as the threshold upper limit and thethreshold lower limit. Furthermore, a configuration example in whichboth the threshold upper limit and the threshold lower limit areprovided will be described; however, the invention is not limitedthereto and any one of the threshold upper limit and the threshold lowerlimit may be provided.

FIG. 24 is a diagram illustrating an example of a procedure related to amonitor information collection process in the embodiment. The sameprocesses as those of the monitor information collection processillustrated in FIG. 12 is denoted by the same reference numerals, and adescription thereof will be omitted.

In step S2401, the monitor information collection unit 204 determineswhether an acquired metric value exceeds a threshold value (whether theacquired metric value exceeds the threshold upper limit and becomes lessthan the threshold lower limit). When it is determined that the acquiredmetric value exceeds the threshold value, the monitor informationcollection unit 204 moves the procedure to step S2402, and when it isdetermined that the acquired metric value does not exceed the thresholdvalue, the monitor information collection unit 204 moves the procedureto step S1206.

In step S2402, based on the configuration information 601, the monitorinformation collection unit 204 determines whether there are resources(related resources) related to a metric of the acquired metric value.When it is determined that there are the related resources, the monitorinformation collection unit 204 moves the procedure to step S2403, andwhen it is determined that there are no related resources, the monitorinformation collection unit 204 moves the procedure to step S1205. Therelated resources indicate a series of resources in which a path hasbeen extended.

In step S2403, the monitor information collection unit 204 acquiresmetric values of the related resources and moves the procedure to stepS1205.

As described above, when the metric value exceeds the threshold value,the metric is not only simply stored, but also stored even though themetric values of the related resources do not exceed the threshold valuebecause there is a potential problem in the related resources in thestorage system. Additionally, since the metric values of the relatedresources are acquired, when the abnormality of the volume 540 isconfirmed for example, all the metric values of resources such as thepool 510, the drive 520, and the port 550 are collated, so that it ispossible to recognize abnormality in the storage system.

In addition, since the summary monitor information 217 is the same asabove, illustration and description thereof will be omitted.

Furthermore, even though the metric values do not exceed the thresholdvalue, the metric values may be configured to be stored for a certainperiod of time (for example, several minutes)

According to the embodiment, the resource status information is storedwhen the resource status information exceeds the threshold value, sothat it is possible to reduce the amount of disk usage.

(5) Other Embodiments

In the above-described embodiments, cases where the invention is appliedto the storage system have been described; however, the invention is notlimited thereto and can be widely applied to other systems, storagedevices, and information management methods.

Furthermore, information of programs, tables, and files for performingeach function in the above-described description can be placed onstorage devices such as other computers, memories, hard disks, and SSDsor recording media such as an IC card, an SD card, and a DVD.

Furthermore, the above-described configurations may be appropriatelymodified, rearranged, combined, or omitted without departing from thescope of the invention.

According to the above-described configurations, the resource statusinformation is appropriately managed, so that for example, the storagesystem can be quickly and easily maintained in a normal state.

Furthermore, according to the above-described configurations, it ispossible to implement a storage system with high maintainability.

1. A storage system comprising a representative node and a plurality ofgeneral nodes including a plurality of resources, wherein each of thegeneral nodes stores first resource status information indicatingrespective statuses of the plurality of resources in a first storageunit thereof, and the representative node: stores second resource statusinformation collected from the plurality of general nodes in a secondstorage unit thereof, wherein the first resource status information andthe second resource status information are different, decides whether toacquire the first resource status information from the first storageunit of one of the plurality of general nodes or to acquire the secondresource status information from the second storage unit by comparing areceived request with the second resource status information, and, whenacquiring the first resource status information from the first storageunit of the general node, decides the general node of the acquisitiondestination from the plurality of general nodes based on the request,and transmits the resource status information acquired from a decidedacquisition destination to an issuing source of the request.
 2. Thestorage system according to claim 1, wherein the representative nodeincludes a plurality of resources, stores first resource statusinformation indicating respective statuses of the plurality of resourcesin a first storage unit thereof, and stores the first resource statusinformation collected from the plurality of first storage units of theplurality of general nodes and the first resource status information inthe first storage unit of the representative node in the second storageunit.
 3. The storage system according to claim 1, wherein therepresentative node determines whether it is possible to acquire thesecond resource status information related to the request from thesecond storage unit, and acquires the first resource status informationfrom the one of the first storage units of the plurality of generalnodes when it is determined that it is not possible to acquire thesecond resource status information related to the request.
 4. Thestorage system according to claim 1, wherein a frequency at which thegeneral nodes acquire first resource status information from eachresource is higher than a frequency at which the representative nodeacquires the second resource status information from the plurality ofgeneral nodes.
 5. The storage system according to claim 1, wherein aperiod for which the representative node stores a history of the secondresource status information is longer than a period for which theplurality of general nodes store a history of the first resource statusinformation.
 6. The storage system according to claim 1, wherein therepresentative node stores summarized resource status information as thesecond resource status information.
 7. The storage system according toclaim 6, wherein the summarized resource status information issummarized in a time direction, and a node that acquires the firstresource status information is decided based on designation of a timeincluded in the request.
 8. The storage system according to claim 6,wherein the summarized resource status information is summarized byaggregating first resource status information of the plurality ofgeneral nodes, and a node that acquires the first resource statusinformation is decided based on designation of a node included in therequest.
 9. The storage system according to claim 1, wherein based on atnumber of the general nodes that performs acquisition when the firstresource status information is acquired from the general nodes, it isdecided whether to acquire the first resource status information fromany one of the general nodes or the second storage unit.
 10. The storagesystem according to claim 1, wherein, the resource can move between theplurality of general nodes, when the first resource status informationis acquired from the general nodes, the representative node acquires thefirst resource status information by specifying a general node based onhistory information indicating any one of the plurality of generalnodes, which is provided with a resource that is a target of the firstresource status information.
 11. A storage system comprising arepresentative node and a plurality of general nodes including aplurality of resources, wherein each of the general nodes storesresource status information indicating respective statuses of theplurality of resources in a first storage unit thereof, therepresentative node stores resource status information collected fromthe plurality of general nodes in a second storage unit thereof, decideswhether to acquire the resource status information from the firststorage unit of the general node or to acquire the resource statusinformation from the second storage unit based on a received request,and transmits the resource status information acquired from a decidedacquisition destination to an issuing source of the request, therepresentative node includes a main representative node and asub-representative node, the main representative node specifies ageneral node that is a target of the received request, specifies arepresentative node, which manages the specified general node, based onmanagement information in which a management relation between therepresentative node and the general node has been defined, and allowsthe specified representative node to acquire the request, and thespecified representative node acquires the request, decides whether toacquire the resource status information from the general node or toacquire the resource status information from the second storage unit,and transmits the resource status information acquired from a decidedacquisition destination to an issuing source of the request.
 12. Astorage system comprising a representative node and a plurality ofgeneral nodes including a plurality of resources, wherein each of thegeneral nodes stores resource status information indicating respectivestatuses of the plurality of resources in a first storage unit thereof,the representative node stores resource status information collectedfrom the plurality of general nodes in a second storage unit thereof,decides whether to acquire the resource status information from thefirst storage unit of the general node or to acquire the resource statusinformation from the second storage unit based on a received request,and transmits the resource status information acquired from a decidedacquisition destination to an issuing source of the request, and themain representative node determines whether the request is to beprocessed by a sub-representative node, which is the specifiedrepresentative node, based on node status information indicating astatus of the main representative node and the sub-representative node,and transmits the request to the sub-representative node when it isdetermined that the request is to be processed.
 13. The storage systemaccording to claim 1, wherein the general node stores first resourcestatus information of a resource of the plurality of resources, in whichthe first resource status information exceeds a threshold value.
 14. Aninformation management method in a storage system including arepresentative node and a plurality of general nodes including aplurality of resources, the method comprising: a first step in whicheach of the general nodes stores first resource status informationindicating respective statuses of the plurality of resources in a firststorage unit thereof; a second step in which the representative nodestores second resource status information collected from the pluralityof general nodes in a second storage unit thereof, wherein the firstresource status information and the second resource status informationare different; and a third step in which the representative node decideswhether to acquire the first resource status information from the firststorage unit of one of the plurality of general nodes or to acquire thesecond resource status information from the second storage unit bycomparing a received request with the second resource statusinformation, and, when acquiring the first resource status informationfrom the first storage unit of the general node, decides the generalnode of the acquisition destination from the plurality of general nodesbased on the request, and transmits the resource status informationacquired from a decided acquisition destination to an issuing source ofthe request.
 15. The storage system according to claim 1, wherein, theresource can move between the plurality of general nodes, when the firstresource status information is acquired from the general nodes, therepresentative node acquires the first resource status information fromthe plurality of general nodes in which its range has been specifiedbased on range information indicating a range of the general nodes inwhich a resource as a target of the first resource status information ismovable.
 16. The storage system according to claim 1, wherein the secondresource status information is, among the first resource statusinformation and second resource status information, information that isrelatively frequently used on a daily basis and needs to be acquiredperiodically.
 17. The storage system according to Additional claim 2,further comprising: monitor management information which is set withinformation included in the first resource information and the secondresource information, wherein the monitor management informationincludes a resource type of a resource status to be collected by thegeneral node with its own node and a collection condition thereof, and aresource type of a resource status to be collected by representativenode from the general node and a collection condition thereof.